Vitamin B12

Cobalamin Test, Cyanocobalamin Test

Results

A vitamin B12 test measures the amount of vitamin B12 in the blood. Normal values may vary from lab to lab.

Vitamin B12

Normal:	More than 200–835 picograms per milliliter (pg/mL)	148–616 picomoles per liter (pmol/L) (SI units)

High values

• High levels of vitamin B12 can occur in liver disease (such as cirrhosis or hepatitis) and some types of leukemia. But the vitamin B12 test is not usually used to diagnose these problems.
• In rare cases, high levels may be found in people with diabetes or who are obese.

Low values

• Low levels of vitamin B12 may mean problems with the absorption of the vitamin (pernicious anemia), hyperthyroidism, or folic acid deficiency anemia.
• Low levels may also occur following removal of part or all of the stomach (gastrectomy), gastric bypass surgery, or gastric stapling surgery, or following surgery to remove part of the small intestine where this vitamin is absorbed (terminal ileum).
• Low levels may mean an infection with a parasite called fish tapeworm is present.
• In rare cases, low levels may mean a person is not getting enough vitamin B12 in his or her food.
• High levels of protein in the blood, such as from multiple myeloma, can falsely decrease blood vitamin B12 levels.

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Author:	Caroline Rea, RN, BS, MS	Last Updated: December 19, 2008
Medical Review:	Anne C. Poinier, MD - Internal Medicine Brian Leber, MDCM, FRCPC - Hematology
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